I am currently in the process of building both a suburito and a bokuto out of bubinga, which is a type of African cherry wood. My wood source guy recommended it to me, and I am happy so far with it. It has a tight, fairly straight grain, which is what you want for wooden weapons. It works really well, and it which is good for those like me who predominantly use hand tools. The drawback is that bubinga is fairly heavy for some weaker wrists and forearms, when compared to other species.

Other than bubinga, I'd have to concur with the above opinions that Japanese white oak and hickory are good functional pieces.